The present invention relates to a gas sensor for measuring the concentrations of gases, in particular of oxygen and at least one further gas, preferably of at least one oxidizable exhaust gas component in the form of a further gas. Moreover, the present invention relates to a device for producing gas sensors, a method for producing gas sensors, a method for measuring the concentrations of gases, a gas sensor device, and the use of a gas sensor.
It is known from DE 196 51 328 B4 that oxygen pumps are based on an electrochemical reaction of zirconium dioxide (ZrO2) between two electrodes. In the oxygen pump, oxygen is transported and/or pumped from one side of a zirconium dioxide wall to the other side by means of the oxygen being reduced to oxygen ions on the cathode, subsequent ion migration of the oxygen ions in the zirconium dioxide, and, lastly, oxidation of the oxygen ions to oxygen on the anode. Due to this effect, a difference in partial pressure on the two sides of the oxygen pump can be attained.
A gas sensor allowing exhaust gas components to be measured is known from DE 10 2007 048 049 A1. The gas sensor comprises a substrate having an electrically insulating surface, for example a body made of Al2O3. In DE 10 2007 048 049 A1, the body is coated with a heating resistor on which a lid made of an ionic conductor (according to DE 10 2007 048 049 A1 this would be an ion conductor made of zirconium dioxide), and the substrate surface forms a hollow space. Metallically conductive electrodes are arranged above and below the ion conductor and two of these are provided as platinum electrodes. Moreover, the gas sensor on the ion conductor comprises a further electrode that is provided as a mixed potential electrode and comprises a precious metal alloy consisting of gold and platinum. The electrodes in this context are porous, such that they are permeable for oxygen. Preferably, they are applied by means of screen printing
DE 197 57 112 A1 discloses a gas sensor for measuring oxygen and/or the air/fuel ratio lambda and at least one further gaseous component, such as, for example, hydrocarbons or nitrogen oxides, in gas mixtures by means of a reference electrode representing a′ constant oxygen partial pressure, an oxygen ion-conducting solid electrolyte, and at least two measuring electrodes, whereby the measuring electrodes and the reference electrode are arranged directly on the solid electrolyte, and have electrical leads for connecting and for detecting the electrical measuring signals. According to DE 197 57 112 A1, the solid electrolyte is provided to be of any geometrical shape and has a side facing the measured gas and a reference side that is separated from the measured gas, whereby the arrangement of the electrodes with the reference electrode on the reference gas side and the at least two measuring electrodes on the measured gas side concurrently yields at least two measuring signals that are based on identical or different, measuring principles and are based on different gaseous components. The sensor is used, for example, for the motor control of motor vehicles.
It is a disadvantage of the prior art, as currently known, that a precise and rapid measurement for the detection of gas concentrations, for example of gas concentrations in exhaust gases, is difficult, time-consuming, and very elaborate.